Scientists achieve quantum teleportation with patterns of light in computing breakthrough
In a step towards quantum communications, researchers have teleported a pattern of light for the first time.
The research means information can be sent more quickly than the methods used previously and “represents the first step towards a quantum network for high-dimensional entangled states” the authors wrote in the paper, in Nature Communications.
In particular, quantum teleportation has the potential to transform the way we communicate, leading to secure communications and an ‘unhackable’ internet.
What is quantum teleportation?
Quantum teleportation works using the quantum principle of entanglement, meaning two particles can be linked regardless of any physical space between them. The quantum state, which could be the spin, position or polarization of the particle, is essentially shared between the two entangled particles.
It uses a combination of classical communication and entanglement to share information about a quantum state between the transmitter and receiver. Two particles are entangled and then sent far away from each other, then information can be shared between the two.
Developments in quantum teleportation have led to it working over a distance of between 500 and 1,400 km between a satellite and Earth.
However, in each experiment so far, the quantum information shared has only had two-dimensional states; for example, spin was only up or down. This limits the amount of information that can be shared.
Orbital angular momentum
In the new paper, researchers have shown how to use higher-dimensional qualities, for something called the orbital angular momentum (OAM) of a photon. There are infinite possibilities for the OAM of photons, and this means more information can be sent at once.
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“Orbital angular momentum allows us to encode lots of information in a single photon,” co-author Professor Jonathan Leach from Herriot-Watt University told Alphr. “It allows us to densely pack information.”
However, the problem comes when trying to keep the OAM in the same state, over long distances. The authors had to devise a way to ‘amplify’ the signal, keeping the OAM information – which they called a quantum repeater.
It works by creating new pairs of entangled photons, out of ones that had never been entangled before – called entanglement swapping. Essentially, a series of repeaters could be placed between the transmitter and receiver, at each step creating new pairs of entangled photons.
“Entanglement swapping may be used to generate remote quantum correlations between particles that have not interacted,” the authors wrote. “This is the core ingredient of a quantum repeater, akin to repeaters in optical fibre networks.”
This allowed the authors to share information across a much longer distance without the need for the information to physically flow over that link.
The paper, the researchers say, is a step towards creating a network of quantum communication.